Fear is one of the most intriguing and misunderstood of all human emotions. It’s necessary for keeping us alive and safe from danger, but having too much fear can be debilitating. A new study has identified the area of the brain responsible for learning fear. This finding not only holds potential for new and more effective phobia therapies, but could also lead to one day being able to prevent our ability to learn fear altogether.
Fear Is Passed On Through Generations, But How?
Scientists have known that a mother’s traumatic experiences can affect her child but have failed to understand why. Children are observed to have fear related to experiences their mother had long before her pregnancy. A new study has identified a potential answer to these phenomena by “showing here that newborns may learn to be afraid of certain cues through experiencing maternal fear behavior in the presence towards these cues,” first author of the study, Dr. Jacek Debiec, told Medical Daily in an email.
Learn Fear From Mothers
Researchers from the University of Michigan taught female rats to fear the smell of peppermint by exposing them to mild, unpleasant electric shocks while they smelled the scent, the press release reported. The pups of rat mothers exposed to the peppermint and pups of control rat mice not taught to fear the scent were then also exposed to the peppermint smell. None of the pups were ever exposed to any of the unpleasant sensations following the scent. To yield the most accurate results, the pups were both exposed to the scent both while in the presence of their mothers and on their own.
Time and again, the pups born from mothers taught to fear the peppermint scent also displayed fear of the same stimuli. The ability of pups to learn fear from adult mice was not limited to mother-child scenarios. “We have shown that “foster mothers” transfer their fear reactions to baby rats in the same way as biological mother do,” Debiec explained.
Ability To Learn Fear Can Be Suppressed
Results from brain imaging and generic activity, genetic activity in the brain cells, and the measurements of cortisol in the blood revealed the lateral amygdala in the brain to be the key location for learning fear. Although the lateral amygdala has been well established as a key region for fear-learning, previous research has shown that in newborns, this fear-learning is naturally suppressed. “Our finding is the first to show that powerful mechanisms of social fear learning – if the mother is the source of fear, baby rats learn to be scared,” Debiec told Medical Daily.
Possibilities For Human Phobias
While the finding is fascinating on its own, its possible implications for human mental health and treatment of phobias are even more exciting. Debiec suggests that there may be ways to prevent children from ever learning irrational or harmful fears, or to even simply reduce the impact of these fears. “We should be more conscientious about early prevention… through studying emotional reactivity of babies of mothers with PTSD we can select the most vulnerable group and start early interventions / treatments,” Debiec explained. However, there is a limit. The study does not suggest a way to prevent future generations from learning to fear all together. “We need fear to survive; we need fear to be who we are,” Debiec insisted.
Although it may be too early to test this odor-based fear effect on human mothers and babies, results from the animal study do suggest that in the case of deeply ingrained fear, there is “something more at work.”
Source: Debiec J, Sullivan RM. Intergenerational transmission of emotional trauma through amygdala-dependent mother-to-infant transfer of specific fear. PNAS. 2014.